predefined argument value to map function. Javascript

Question

var i = [1,2,3,4,6,7];
var k = i.map( (data, i) => { if(data==1) return 2; else return data; } );
console.log(k);

This program is going to output [2,2,3,4,6,7]

I am changing value of k based on a specific value. How can i change the value according to a specific array index using map function?

like how we do normally, array[index] = somevalue;

why do you need to iterate if you have already an index for changing? — Nina Scholz
– Nina Scholz, Commented Mar 14, 2017 at 20:14
developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Heretic Monkey
– Heretic Monkey, Commented Mar 14, 2017 at 20:14
If you are only changing a specific array index, just clone the array and then set that particular element. k=i.slice(); k[index] = somevalue; — Patrick Evans
– Patrick Evans, Commented Mar 14, 2017 at 20:15

Nina Scholz · Accepted Answer · 2017-03-14 20:39:10Z

1

You could check with the index of the array while iterating, with the wanted index and return a selected value or the original value.

var array = [1, 2, 3, 4, 6, 7],
    index = 3,
    result = array.map((a, i) => i === index ? 42 : a);

console.log(result);

answered Mar 14, 2017 at 20:27

Nina Scholz

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